Commercially available solenoid operated valves typically are available in sizes down to a minimum 6 mm in diameter. Although valves smaller than 4.5 mm exist, the valves are much smaller, and are based on alternate construction and/or actuation techniques such as MEMS. In general, smaller solenoid based valves do not exist, because as the solenoid decreases in size, the work capability of the solenoid is reduced to the point where the solenoid is incapable of providing operation of the valve for the desired valve pressures and flow rates. It would be desirable in the present invention to provide an electrically actuated valve capable of being sized to 4.5 mm or less.
Commercially available solenoid actuated proportional valves are typically no smaller than 15 mm in diameter. The issue is not merely the raw power of the electromagnetic field as the coil decreases, but rather the ability to control the operation of the valve in a predictable linear fashion is extremely difficult. Further, a proportional valve is continually operating, thus typically requiring greater heat dissipation/handling ability than a simple on/off valve. It would be desirable to provide an electrically actuated valve capable of two-way or three-way operation, and capable of either on/off mode of operation or proportional mode of operation.
Typical commercially available solenoid valves respond with times in a range from 5 ms to 20 ms. Higher speed for the solenoids can be achieved, but generally require special electronic control such as overexcitation or special coil construction. It would be desirable to provide an electrically actuated, direct acting valve capable of response times in a range less than 5 ms, and preferably approximately 1 ms.
Commercially available, competitively sized valves based on solenoid actuation generally are sized on the order of 6 mm to 16 mm pitch and can exceed 22 mm. Further, the commercially available solenoid valves generally consume between 0.5 and 4.0 watts. Other piezo valves have lower power consumption compared to such solenoid actuated valves, but none of the piezo valves have the desired level of flow and pressure capability on a direct acting basis in as narrow a size. Piezo valves that do have the desired level of pressure and flow capability typically reach the desired levels when acting as a pilot valve for a larger valve, where the larger valve provides the desired level of pressure and flow capability. Alternatively, piezo valves can reach the desired performance levels but require greater width. It would be desirable in the present invention to provide a direct acting electrically actuated valve with high pressure and high flow capabilities without acting as a pilot valve for a larger valve and with a narrow width.
Although narrower examples are available, commercially available proportional valves can be, for example, approximately 22.2 mm in diameter and 39.6 mm tall. The version of such a commercially available proportional valve with an orifice size of ˜1.5 mm can flow up to fourteen standard liters per minute (slpm) at the maximum pressure of twenty-five pounds per square inch (psi). Further, the maximum rated pressure at any flow for the commercially available proportional valve is 100 psi. It would be desirable to provide an electrically actuated proportional valve which can operate at over 120 psi with a 1.5 mm equivalent orifice, and to provide an electrically actuated proportional valve which at 80 psi can flow up to approximately 50 slpm.